Agree with NoD that in some circumstances you could reject and stop safely above your bugged V1. (Bugged V1 is Vmcg, but high range V1 is coincidental with Vr)
In a B737/A320 type operation with typically less than 2 or 3 seconds between V1 and Vr, do we realistically have the time and/or capacity to make a judgment call of the magnitude of rejecting above V1? I was always told if anything goes wrong, sit on your hands and then calmly decide what to do. In circumstances where this is inappropriate and instantaneous reactions are required, we have well drilled and practiced memory items to be followed to ensure the safest outcome. The definitive example would surely be an engine fire between V1 and V2!
At the company I work for, we use low range V1s on the principle that statistically less accidents have occurred by continuing the take off when compared to high speed rejects.